Problem: $ { {2} \times \left[\begin{array}{rr}{-1} & {0} \\ {0} & {2} \\ {1} & {4}\end{array}\right] = {?} } $
Answer: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{2}\times{-1} & {2}\times{0} \\ {2}\times{0} & {2}\times{2} \\ {2}\times{1} & {2}\times{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-2} & {0} \\ {0} & {4} \\ {2} & {8}\end{array}\right]}$